Sheet-heating furnace.



C. ELLIS.

SHEET HEATING FURNACE.

APPLICATION FILED NOV; 4. 1912. RENEWED 05c. 29. less.

Patented Aug. 21, 1917.

m H n CETON ELLIS, 0F MONTCLAIR, NEW JERSEY, A SSIGNOR TO RADIANT HEATING- unnv, rnnns, ENGLAND, n oonronarron or GREAT BRITAIN.

emnr-nnarnve FNACE.

Specification of Letters Patent. Patented, Aug. 21, 191'] a Application filed November 4, 1912, Serial No. 729,316. Renewed December 29, 191 6. Serial No. 139,704.

To all whom it may concern:

Beit known that I, Cameron Ems, a

' citizen of the United States, and resident of Montclair, Essex county, New Jersey, have made certain new and useful Invention Re -Q lating to Sheet-Heating Furnaces, of which the following is a specification, taken in con nection with the accompanying drawing, which formspart of the same. y

This invention relates to furnaces which are adapted to heat sheets of steel or other articles as in connection with forging or 8 stamping operations, the furnace comprising azfurnace' chamber and connected flue and one or more heating devices cooperating with the chamber so as to communicate therethrough with the flue, means, most de sirably a conveyer, being provided to carry the plates or other articles through the chamber from the flue end toward the heating devices. and admission and discharge 7 doors being preferably used in cooperation with the conveyer." The heating devices comprise most desirably a lower granular bed and also in some cases an upper inverted granular bed having their incandescent working faces arranged to cooperate with the articles in the furnace,each of the granular .bedsbeing composed of granules of refractory material heated by the combustion therein of injected explosive gaseous material supplied through injecting aper ill tures which are preferably substantially uniformly, spaced apart at suitable distances between centers to insure substantial uniformity of heating throughout the incandescent working faces of these granular beds which can thus quickly and uniformly heat 4 the plates or othe; articles 'while the hot combustion gases may be used to preheat the approaching articles to a greater or less extent according to the length of the furnace chamber. 1 In the accompanying drawing showing 111 a somewhat diagrammatic way illustrative embodiments of this invention, Figure 1 is a sectional elevation. Fig. 2 is an enlarged sectional view of one of the granular beds or heating devices.

Fig. 3 is a plan view thereof. 4 Fig.- 4 is a diagrammatic view on alarger I scale showing the arrangement of ln ecting apertures and heat zones; and- Fig. 5 is a corresponding enlarged secgioial view through part of the granular e 2 ,The furnace, as diagrammatically illustrated in the drawing, comprises a suitable I furnace chamber 1 having walls of refractory material and provided with a flue connection 10 adjacent one end. A suitable conveyor 2 may be arranged-to pass through the furnace or have its lateral conveyor chains or carriers mounted in the sides thereof, as is usual, and this conveyer 2 carrying the steel plates or other articles 3 through thefurn'ace may be operated by the may be mounted at the admission end of the furnace adjacent the flue and similar discharge doors 12 may be mounted adjacent the heating devices so as to insure the proper circulation of hot gases through the furnace.

As indicated the heating devices employed may be of the granular bed type, one or morecombustion beds of granular. material being mounted with their incandescent work ing faces closely adjacent the path of the articles on the conveyor so as to quickly and v uniformlyflheat these articles. by the intense and substantially flameless'combustion of explosive gaseous mixtures within the granular. "beds of refractory combustion accelerating material as described in the U. S. patents, Luoke, No. 755,376, and Bone, Wilson & Mc- Court, No; 1,015,261; that is,'the explosive gaseous mixture entering the refractory bed with a velocity in excess of the speed of backfiring is caused to spread out and have its velocityrapidly reduced as it advances through the bed. until it reaches a surface 01'.

zone at which the velocity of the mixture equals the rate of back-firing at which sur-- face or zone combustion takes place, the combustionbeing thus localized within the bed. The lower heating device may be in the form of the granular bed 8, the substantially.

uniformly sized granules of refractory com :bustion accelerating materi, so as alu mina, magnesite or even refractory fire'clay for the lower heats being of about one-half .or three-quarters inch mesh and arranged within asuitable refractory lining, such as 6, so that the upper or working face of this granular bed which is heated to incandescence under operating conditions is preferably relatively closer than indicated in the drawing to the articles and arranged Within a few inches of them for most rapid work. If desired, an upper inverted-1 granular bed 28 may also be arranged at the top of this part of the furnace chamber, the refractory granules 28 being permanently secured in} 'position in the refractory bed liningv 26*as by coating the particles witha small amount of relatively fusibleor fluxingmaterial and then calcining the bed and lining at an intensely high. temperature so as to cause the refractory granules'to permanently unite together and to the bed lining by fusing or fluxing together their contacting portions at heats'considerably in excessof any working temperatures to which they are subsequently subjected. In this way, as indicated, in

- Figs. 1 and 5, the granules are permanently secured together in such way as to leave numerous tortuous passages between these rough porous, granules substantially similar to the passages between a loosely piled bed of such rough porous lumps or granules of refractory material. I V

Thesegranular beds may be heated by injecting thereinto explosive gaseous mix-'- tures of any suitable combustible gas or vapor and air or other supporter of: combustion therefor preferably in about the proportions required to secure complete combustion for greatest efliciency, although of course byusing a slight excess of the combustible gas a slightly reducing atmosphere may be maintained in the furnace which minimizes oxidation. The explosive gaseous mixture is injected into the granular bed through injecting apertures 13 which are preferably uniformly spaced throughout the bed to secure uniformity ofheating and these injecting nozzles or apertures 13 are preferably so spaced as to secure sufficient overlapping or approximation of the heat zones produced by each of the injecting apertures to secure substantiahuniformity of heating throughout the bed which is .a

"highly desirable feature especially in heating thin plates or the like. Formoderate' sized injecting apertures of three eighths of an inch to an inch or' so diameter through which ordinary coal gas 'or enriched. producer gas is injected after mixture with air of about a pound or so pressure which gives sufficient velocity to prevent back-firing through the injector apertures, the spacing of the injector apertures and the thickness of the granular bed togive a most effective and uniform heat should apparently bear a substantially fixed ratio to the size of the apertures, uniform heating results being secured when D=4:A and CIQDISA as determined by ail extended series of em pirical tests; where D" is the depth of the granular bed, A is the diameter of the injecting apertures and C the center distance between apertures, that is, the distance between the center lines of adjacent apertures as indicated in Figs. 4 and 5. Under these circumstances, the heating zones fromeach aperture, while of course somewhat irregular because of the tortuous character and irregular section of the channels through the granular bed, have approximately such ing beds makes possible the burning of un-- usual quantities of gaseous fuel within a very restricted space, the rate of combustion being accelerated many times beyond that occurring in ordinary flame combustion, so that in this way extremely rapid as well as uniform heating can beef'fected because of the extremely high temperatures secured in the working faces of the incandescent bed and the correspondingly great radiating efficiency thereof. This is of great importance in many stamping and forging operations, especially where thin steel or iron plates are involved, although of course similar granular bed heating units are useful in other c onnections where intense and uniformheatsare desired.

The explosive gaseous mixtures may be conveniently fed to the granular material by any suitable arrangement, such for example as the supply pipes -7 shown in Figs. -1, 2 and 3 as connecting the lines of nozzles 13 communicating with each of the injecting apertures and these supply pipes may of course be connected to suitablefsupply lines such as 17 fed with explosive gaseous mix-' tures. which-may be supplied under the desired pressure by any form of pumps or other devices. The supply line may as indicated have a suitable Y connection, the air connection 18 leading to a suitable air pump 19 and receiving therefrom air under pres sure which has been drawn from the air line 20. The gas connection 21 similarly receives the combustible gas or vapor from the gas pump22 which draws the gas from the gas I line 23 so that in this way a substantially uniform explosive mixture of, gas and air can be conveniently secured preferably. containing a slight excess of gas where teel plates by the conveyer into position between theheating devices are of course very rapidly and highly heated 'by radiant heat from the highly incandescent Working faces of the granular beds so that it, is not only possible to secure a rapid heating of the articles, but by regulating the, amount of fuel burned in the granular beds it is possible to accurately time the feed or supply of these heated articles to apress or forging device so that much more satisfactory results can be secured because of the uniformity .of the forging or stamping conditions. Of course by conducting the intensely hot combustion gases along the furnece chamber in the opposite direction to'the articles fed along toward the heating devices a considerable preheating can be secured depending upcn the length of furnace chamber employed and a corresponding economy in fuel consumption effected.

By the term explosive gaseous mixture as used herein is meant'a mixture of a suitable combustion supporting gas, either oxygen alone or air or otheroxygen containing gas, with combustible matter'in a gaseous or other finely divided state in proportions such that the mixture will have the property of self-propagation of inflammation. Such proportions may be the chemical combining proportions or there may, of course, bean excess of either the combustible matter or the combustion supporting gas within the limits which determine the property of self-propagation. The mixture may be varied in this respect according to the desired character of the products of combustion.

Having described this'invention in connection with an illustrative ,embodiment thereof, to the details of which disclosure the invention is not of course to be limited, what is claimed as new and What is desired to be secured by Letters Patent is set forth in the appended claims.

1. A heating furnace comprising in combination a furnace chamber, means for conveying articles to be heated through the furnace chamber, means for burning an explosive gaseous mixture adjacent the path of travel of the articles to be heated and for permitting the products of combustion to i enter the furnace chamber, and a flue leading from the furnace chamber at a point distant from the place of combustion in a direction longitudinal of the path of movement of the articles to be heated.

2. A heating furnace comprising in combination a furnace chamber, a heating devicecommunicating with the furnace chamber, a flue leading from the furnace chamber at a point distant from the heating de-' vice,,and means for conveying articles to be heated through the chamber in the direction from said flue to the heating device, said heating device comprising means for burning an explosive gaseous mixture ad acent the ath of travel of the articles to. be heated and for permitting the products of such combustion to'enter the furnace chamber.

3. A heating furnace comprising in combination a furnace chamber, a heating device communicating with the furnace chamber, a flue leading from the furnace chamber at a point distant from the heating device, and

means for conveying articles to be heated throughsthe furnace chamber in the direct1on from said flue to the heating device, said heating device comprising a porous bed of refractory material in close proximity to thepath of travel of the articles to be heated, and means for supplying tosaid bed an explosivegaseous mixture at a velocity lIl excessmixture. J p

4. A heating furnace comprising in combination a furnace chamber, heating devices communicating with the furnacechamber, a

of the speed of back-firing of the flue leading from the furnace chamber at a point distant from the heatingdevices, means for conveying articles to be heated through the furnace chamber in the direction from' said flue to'theheating devices,

said heating devices comprising porous beds of refractory material set on opposite sides of the path of travel of the articles to be heated and, in close .proximity thereto, and means for supplying to said beds an explosive gaseous mixture moving with a velocity in excess of the speed of back-firing of the mixture.

5. A heating furnace comprisingin combination a furnace chamber, means for conveying articles to be heated through said chamber, an inverted porous bed of refractory material set above and in close proximity to the path of travel'of the articles to be-heat'ed, means for supplyingan explosivegaseous mixture to said bed to burn.

therein and to heat the face thereof adja-' cent the path of travel of the articles to be heated to 'incandescence, and a flue leading from the furnace chamber at a point" distant from said combustion bed;

6. A sheet heating furnace comprising in combination a furnace chamber, means for conveying sheets or plates to be heated through said chamber, heating means com-- prising a lower porous bed of refractory material and an upper inverted porous bed of refractory material set adjacent the am of travel of ,the sheets or plates to be eated,

means for supplying an explosive gaseous chamber in the direction opposite to the dimixtureto' said beds to burn therein and to rection of movement of the sheets or plates 10 heat the fafies thereof adjacent the pith o; to beheated.

travel of t e s eets 01' plates to be eate 5 to incandescence, and a flue leading from the E N- ELLIS furnace chamber ata point distant from Witnesses:

the heating means in the direction to cause HENRY EDMUNDs, the combustion gases to move through the JESSIE B. KAY. 

